In recent years, the ink jet technology has been expected for use as manufacturing apparatuses, not merely as printer devices for forming images on paper mediums. For example, in JP 2003-191462 A, an apparatus construction in which droplet ejecting elements using the ink jet system are mounted is disclosed as a manufacturing apparatus for liquid crystal displays, organic EL displays, plasma displays, electron emission elements, electrophoretic display devices and the like. For improvement of landing position precision onto the substrate, in JP 2003-191462 A, a stage for carrying the substrate in one fixed direction with an apparatus base body provided by a granite surface plate, and a carriage mechanism for moving an ink jet head along a direction perpendicular to the stage traveling direction, are provided on the granite surface plate in direct connection.
A general-use printer by the ink jet system, typically, forms images by using one ink jet head unit on which several pieces of ink jet head elements each having a width of ½ to 2 inches and having nozzle openings regularly arrayed at intervals of 150 to 300 nozzles/inch are mounted as elements for ejecting droplets in some plural quantity for each of the individual colors. As the method therefor, it has been practiced that recording sheet, while fed by a sheet feed roller, is scanned a plurality of times in a direction perpendicular to the carrying direction of the recording sheet so that an image is formed on the recording sheet.
Even with the use of the ink jet system as a manufacturing apparatus, the ink jet head elements are similar to those of general-purpose printers, the size of each ink jet head element in the nozzle array direction being 1 to 2 inches at most as it stands.
Meanwhile, manufacturing processes for liquid crystal displays, organic EL displays, plasma displays, electron emission elements and electrophoretic display devices are increasingly directed toward increasing the yield quantity by using larger-area substrates to reduce the cost and the cycle time. Manufacturing of these devices and others by the ink jet system would require an apparatus that is capable of managing large-area substrates having one side as much as several meters.
One of manufacturing apparatuses using the ink jet system capable of high-speed processing with large-area substrates is a line head system in which a plurality of ink jet head elements are arrayed to a length more than the substrate size. This system is so configured that at most 1 to 2-inch wide ink jet elements are staggered to an extent equal to the substrate size, in which case at least 100 to 200 heads need to be arrayed on condition that the substrate is several-meter sized. Apparatuses by this system can be said to be quite effective in cases where ejection to all over the substrate such as color filter substrates is required and moreover the ejection points are regularly located.
However, the line head system would be unsuitable for recovery of color filter substrates as shown in, for example, JP 2003-66218 A. JP 2003-66218 A shows a system which includes, as part of the manufacturing method of color filter substrates, ejecting a color filter material only to failure points on occurrence of coloring failure portions in the color filter substrate. Using the line head system as a means for correcting such failure points scattered on the color filter substrate would involve the same processing time as in the ejection of droplets to all over the substrate, and moreover cause most of the nozzles to be non-operating nozzles that perform almost no ejecting operation, leading to a high likelihood of occurrence of nozzle clogging. Further, maintenance operation would be required for all the nozzles, leading to increases in unnecessary waste fluids. Also, with a desire for uniformized ejection quantity, the line head system would give rise to a need for performing ejection quantity correction on a total of thousands of nozzles, one by one, despite the purpose of merely ejecting droplets to scattered desired points, hence extremely inefficient.
Further, in a system in which the ink jet head unit that has been widely used in general-purpose printers is reciprocated in plurality on one identical plane, the scanning distance of the ink jet head units is increased, and the scanning speed is also limitative in terms of stable operation, so that the processing time could not be shortened.
Furthermore, the desire for efficiently ejecting droplets to desired points without limitation to all over large-area substrates is what will be sought in the future not only for recovery of color filters but in various manufacturing fields.
Also, with the use of the ink jet system as a manufacturing apparatus, not only the cycle time related to the droplet application onto the substrate but also the cycle time for the other processes needs to be shortened. That is, it is desired to shorten a total time including the time for introduction and carry-out of the substrate, the attitude control time of the introduced substrate, and the time from the completion of attitude control to the start of droplet application operation.
Meanwhile, there has been a demand for enhancement toward higher precision of attitude control (e.g., within an error of 1 μm or less). Thus, the shortening of the attitude control time and the enhancement toward higher precision of the attitude control has been in a trade-off relation.
For example, JP 2000-329516 A discloses alignment marks related to bonding of two substrates. More specifically, in this disclose, coarse alignment is carried out with a low-magnification field of view by devising the configuration pattern of negative and positive two alignment marks, so that high-precision alignment is achieved only with a low-magnification field of view without involving precision alignment with a high-magnification field of view.
Besides, alignment performance depends on the resolution of a CCD camera, which is an image pickup means, and the resolution generally depends on the number of pixels of the CCD camera and the area of the field of view. Therefore, satisfying desired alignment precision requires, in JP 2000-329516 A, setting the field of view to a high magnification. In this case, the mark does not come within the field of view in early alignment, giving rise to a need for repetitively searching the mark, with the result that longer alignment time would be taken in some cases.